Lecture 21

Question 1

Life histories:

Answer 1

are sets of evolved traits having to do with survival and reproduction

Question 2

what is difficult in determining with life histories?

Answer 2

determining cause and effect

Question 3

a main trade off is survival vs ——-

Answer 3

fecundity

Question 4

if there is high adult mortality what happens wth fecundity?

Answer 4

age at maturity decreases with increasing annual adult mortality

Question 5

aging or sescence:

Answer 5

is a late life decline in an individuals fertility and probability of survival

Question 6

the rate of living theory:

Answer 6

aging caused by the accumulation of irreparable amage to cells and tissues. Organisms have reached their limit of biological repair. There is a lack of genetic variation that would enable them to evolve more effective repair mechanisms

Question 7

The ROL theory predicts:

Answer 7

life span should correlate negatively with metabolic rate

Question 8

Why are bird the puzzling?

Answer 8

despite having high metabolic rates for their body size compared to mammals they often have longer lifespans than a mammal of the same size. Birds seem to have evolved mechanisms of protecting tissues from being damaged by free radicals

Question 9

Most birds have what kind of survivorship curve?

Answer 9

type 2

Question 10

incubation efficiency improve with —–

Answer 10

age

Question 11

factors that influence clutch size within a species include:

Answer 11

1. age - older females typically have larger clutches
2. season- in temperate areas clutches are typically smaller later in season
3. food availability- clutch typically larger with increased availability of food
4. Latitude: clutch sizes are typically larger at higher latitudes

Question 12

what does this image tell you?

Answer 12

larger clutch sizes to north, temperat and arctic and lower in tropics

Question 13

5 explanations for the latitude trend:

Answer 13

1. Day Length- arctic has longer days and more foraging time.
2. Diversity of prey greater in tropucs therefore more challenging to forage efficicenty if you have to search for so many different prey and environment complex. Arctic specializes on one prey
3. Food abundance and interspecific competition: in the temperate sone because of migrations there is no birds in spring and pulse of food. Tropics have more competition
4. predaton: is higher in tropics generally and we have seen that when there is predators parents minimize time going to and from nest to not attract them.
5. Adult longetivity: temperate birds have shorter lives because of migrations so tropical birds have longer life span and a reason why they have smaller clutch sizes.

Question 14

there is a gradual ——- relationship betwen how many children an adult raises and the adults survival

Answer 14

negative

Question 15

secpnd trade off with reproduction and survival…

Answer 15

how many offspring should an individual produce in a year. the more offspring the less each will be cared for and an increase in adult death

Question 16

David Lack 1947 suggested what?

Answer 16

that selection would favor the clutch size that produced the most surviving offspring

Question 17

Lack proposed 3 things:

Answer 17

1. For preocial species, clutch size was limited by the egg formation ability of the female
2. For other species, clutch size was limited by the parents ability to feed the yonug.
3. The modal clutch size in a population should be the most productive, on average

Question 18

Lacks hypothesis for the evolution of clutch size assumes what?

Answer 18

a trade-off between probability of individual survival and clutch size.

Question 19

how do we explain the observation that many birds appear to lay clutches that are smaller than the apparent optimum?

Answer 19

1. Trade off between current and future reproduction. Lay large brood, smaller one next year.
2. Increasing clutch size may reduce the quality of the offspring. More productive clutch size is smaller than that which produces the most surviving.
3. optimal clutch size may vary from year-tp year depending on availability of resources

Question 20

what was the difference between lack and skutch and Moreau for the driving factor?

Answer 20

Lack emphasized food and foraging ability as the driving factor in the evolution of clutch size

Skutch and Moreau emphasized population density as a regulatory mechanism

Question 21

seasonality hypothesis:

Answer 21

clutch sizes in some birds may be influenced by variation in the seasonal availability of resources or, for resident species, resource availability in winter within a birds territory largely determines clutch size. Birds in seasonal habitats have larger clutches than in the tropics where the environment is more stable

Question 22

the predation hypothesis:

Answer 22

high predation rates could select for smaller clutches because it takes longer to lay a large clutch than a small one. Larger broods are noisier and require more nest visits by adults. Where risk of predation is great, it may be better to risk fewwer eggs and young at a time (siberian jays)